It is very rare for a cross posted article to RRS to be useful. Most are Trolls. I enjoyed your web page on scrounging. I'm taken aback on the prices that you posted about equipment however quoted below.
A TDS7104 sold new in the $30K to $40K range depending on options. I have priced this scope at used equipment resellers in the $8 to $10K range. The equipment is sold in calibration and working with a short warranty like 30 days for verification that the equipment is in proper working condition from resellers.
At prices under $1K even with no guarantees I expect this equipment is hot at those prices. All equipment from the major makers have serial numbers throughout the equipment and in the firmware. If you ever send this equipment in for repair you might be in for an unpleasant surprise.
In the last few years there is a new class of scope called real time. The reason I'm responding to this thread is that you just happened to mention a real time scope the TDS7104. Tek calls real time scopes DPO or Digital Phosphor scopes. Most digital scope are repetitive sampling making them a poor choice for low frequency events like an intermittent pulse and these are useless for high speed single shot events. The DPO's resemble an analog scope with memory. There are the best suited digital type for single shot or low frequently occurring events. The DPO's are designed for a very high re-acquisition rate compared to digital sampling types, which is why they are better suited for the low frequency events as they are more likely to be actually sampling the input during an event rather than being in another part of the processing cycle. DPO's have a rapid processing cycle and also have most of that cycle being actual sample time so they are able to catch that infrequent pulse. The repetitive sample high speed scopes generally have cycle times of 200KHz or slower and most of that cycle time is signal processing and display. Repetitive sampling scopes are good at any type of recurring signal like clocks. They are poor choice at looking at data streams with long patterns. The only way you can look at long patterns is at the bit level or eye mode.